Apparatus for oiling sheet metal



R. A. WOOFTER ET AL APPARATUS FOR OILING SHEET METAL 2 Sheets-Sheet 1 Filed NOV. 2'7, 1944 INVENTORS rfi $1 W2 M H i W} MW 7 we. Z w y 2 Oct. 28, 1947.

Oct. 28, 1947. R. A.. WOOFTER ET AL APPARATUS FOR OILING SHEET METAL Filed Nov. 27, 1944 2 Sheets-Sheet 2 INVENTORS Patented Oct. 28, 1947 s PATENT OFFICE APPARATUS FOR OILING SHEET METAL Robert A. Woofter, Emsworth, andRobert H. Smith, Avalon, Pa., assignors to Jones & Langhlin Steel Corporation, Pittsburgh, Pa., a corporation of Pennsylvania Application November 2'1, 1944, Serial No. 565,314 I 'This invention relates to the oiling of sheet metal, such as tinplate, in continuous strip, and more particularly to anapparatus for applying a very thin film of oil to electrotinned strip.

An object of the invention is to provide an apparatus for applying to sheet metal, such as tinplate, a film of oil of uniform thickness sufiicient to protect'the metal during storage and shipment, but not so thick as to interfere with subsequent processing.

In the manufacture of tinplate, for example, it is highly desirable to have a thin film of oil on the surface of the plate when it is packaged for shipment, for several reasons. If the plate is packaged without oiling and is stored for a period of time prior to use, it may rust in spots, particularly if stored in damp or humid surroundings. If the plate is packaged without oiling and roughly handled in shipment the individual sheets or plates may rub upon one another sufiiciently to produce blackspots on the coatinga form of tin oxide objectionable to the user. And finally, unoiled sheets, after having been stacked, tend to stick together and so jam the automatic feeding machines used by can makers.

' For certain applications, however, the thickness of this oil film must be kept to a minimum. Light weight tinplatethat is, plate with a thin tin coating-is quite generally lacquered or enamelled by ,the can maker for a number of types of cans, and this lacquer or enamel does not adhere well if an appreciable amount of oil is found on the tinplate. Thus the tinplate producer encounters difilculty in applying enough oil to protect the 3 Claims. (CI. 91-55) therefore highly desirable to apply the oil to the continuous strip. Because of this, the methods of controlling the oil thickness employed for hot dip tinplate, which is produced commercially as separate sheets, are not readily applicable, and in any case are not satisfactory. Conventional methods, such as oiling by spraying or dipping the sheet, or dipping followed by branning to remove excess oil, have been adapted to continuous strip but have been found incapable of producing a uniform oil film of the desired thinness. The method has been reversed, and a fixed quantity of oil added to the bran, through which the strip is then run, but also without the desired result. Other processes have been tried, but it can be said of the oil films they deposit, that; those providing protection impair lacquer adhesion, and those which do not impair lacquer adhesion do not provide suflicient protection.

plate in shipment but not so much as to impair lacquer adhesion,

This problem is most-acute with electrolytically tinned sheets. 'I'he'great bulk of electrolytic tinplate is made with thin tin coatings, on the order of k to lb. of tin per base box of plate. A base box "of tinplate contains sheets totalling 217.78 sq. ft. of surface, one side. Nearly all of this product is lacquered by the can maker. Although oil is widely used in the brightening stage of the manufacture of electrolytic tinplate, the film left on the plate is generally not the weight and type desired by the user and therefore the finished platemust 'be oiled as a separate step in the production process. It is with this step in the manufacture of tinplate that our invention is concerned.

Electrolytic tinplate is all produced as continuous strip, and is only sheared to sheets as the last step before sorting and packaging. It is Prior to our invention, no method of oiling electrolytically tinned strip was known which deposited a film suilicient to provide protection in storage and transit but thin enough not to impair lacquer adherence.

We have invented an apparatus for continuously oiling strip which produces an exceedingly thin but continuous film of oil on the metal surface, suflicient to provide protection in storage and transit, and not detrimental to lacquer adhesion.

Our apparatus provides means for atomizing oil with air to form a mist of oil particles suspended in air, means for heating such a mist to vaporize the oil particles,and means for finally causing the oil vapor so formed to condense on the surfaces of the strip. We find that by these means we can deposit on the metal an oil film so thin that only .1 of a gram of oil is suflicient for a base box, or one pound of oil covers 2,000,000 sq. ft. of surface; such a film has been found to have no detrimental eiiect on lacquer adhesion. This film, moreover, is so uniform, and covers the surface of the tinplate so completely that it provides adequateprotection to the plate.

In the accompanying drawings which illustrate a preferred embodiment of our invention:

Figure 1 is a vertical longitudinal section illustrating the general arrangement of our apparatus, parts being broken away and other parts being shown in elevation and Figure 2 is a vertical section through one of the spraying devices.

Our process is most conveniently carried out in a point at the tin line just before the final coiler, where the strip can be made to run vertically.

,droplets or particles suspended in air.

. y 3 As shown in Figure l, a continuous tinplated strip 2 coming from the .electrotinning line passes around rollers 3, I and and then upwardly between rollers 3 at the top of the apparatus and then downwardly around one of the rollers and around a roller I and over a roller 8 to a coiler 9. In traveling upwardly between the rollers 5 and 6, the strip passes first through a vaporizing chamber in formed by upper plates I I and lower plates 12 and ,then through a cooling chamber 13 formed by a; housing ll. On each side of the strip and located in the vaporizing chamber is a row of atomizing nozzles l5, each of which provides a stream of oil mist consisting of oil particles suspended in air. These nozzles and associated parts are described in more detail hereinafter in connection with Figure 2. The atomizing nozzles may be of any type which thoroughly atomizes the oil, that is to say which forms a mist of oil The air and oil may or may not be heated; in the case of an oil such as palm oil or paramn which is a solid at ordinary temperatures sufficient heat to liquefy the oil is, of course, essential. It is generally desirable to heat the air to insure its dryness but neither the oil nor air is heated to a temperature much higher than 200 F. In any case after passing through the spray nozzles IS, the mist or oil-air mixture is probably cooled to a temperature near room temperature by the expansion. The nozzles l5 are preferably placed about 6 to '1 inches from the strip and the streams of oil mist are directed as shown by the reference numeral l6 and impinge first upon the baflies l1 and then rebound to baiiies l8 by which they are directed toward the strip 2. The baiiies l1 and it are heated by any convenient means such as by electricity to temperatures high enough to cause the oil particles in the mist to vaporize and are so placed that no particles of unvaporized oil impinge on the strip. The oil vapor thus created condenses on the strip l as it passes through the cooling chamber I3, the strip being approximately at room temperature.

The thickness of the oil film deposited is most conveniently controlled by controlling the amount of oil fed to the atomizer nozzles. If our apparatus is placed in the tinplating line, as mentioned, the speed of the strip is determined by the operating conditions of the line, and may vary as it is taken up or let out of the looping towers. If the oil film is to be uniform, therefore, the oil pumps should be driven from the tin line drive itself, directly or indirectly.

The amount of heat necessary to introduce into the baffles IT and I8 is quite easily determined from observation. If the baffles are observed to be wet, not all the oil is being vaporized, and more heat is required. If the battles are too hot, some oil will burn, producing smoke which is easily detected. For cottonseed oil, we find that each bailie, if electrically heated, requires about 100 watts per inch width of strip. The temperature of the heaters may be controlled by con- 4 pipes 22, 23 and 24. The oil flows through an opening 25 in the pipe 24 into the trough 2| and the overflow passes over a dam 26 into a sump or return 2'! from which it is returned to a pump (not'shown). The housing maybe provided, if desired, with an electrical heater 28 for heating the oil. Wheels or discs 23 are mounted on a shaft 30, the shaft being driven directly or indirectly from the driving means for the strip so thatthe shaft and wheels 29 rotate in accord ance with the speed of passage of the strip through the apparatus. A nozzle 3| is located above each wheel 29. The nozzle is provided with a passage 32 controlled by a valve 33, the passage communicating with a pipe 34 which supplies air. Adjacent the outlet of the air passage 32 is a plate 35 which directs the air downwardly past a hole 36 formed in the nozzle. The hole 33 is located adjacent a shoulder 31.

As the wheel 29 is rotated, it picks up a film of oil from the oil in the trough 2| and raises it to a point adjacent the hole 36 where the film of oil is scraped off by the shoulder 31 and fiows through the hole 36 in a very fine stream. The oil issuing from the opening 36 is atomized by the air fiowinglthrough the passage 38 forming a mist of oil droplets or particles suspended in air. This stream of mist is directed against the heated baflies I1 and I8 as previously described and the mist is condensed on the strip 2. In the embodiment shown, the air nozzles 3| and discs 29 are spaced about 1 inch apart over the width of the strip. This spray produces a very uniform oil mist because the rotating discs 29 bring up 011 to the air stream at a rate varying only with the speed of rotation of the'shaft 30. The amount of oil atomized is thus easily controlled by controlling'the speed of rotation of the shaft.

The pressure of air required is low, 2 to 4 lbs. being satisfactory, except When the air flow is also used to control the battle temperature as previously mentioned. Under such conditions, pressures 'up to 12 lbs. have been employed, with satisfactory results.

The type of oil used depends, of course. on the customer's requirements. Palm oil is occasionally used by us for electrolytic plate, but cottonseed oil is more generally employed. For some purposes a synthetic compound such as di-butyl sebacate is more desirable. Paramn oil, and hydrogenated fish oil have also been used occasionally. It is understood that our process is capable of utilizing any oil required and is not limited as to type of lubricant. As has been mentioned, our process is capable of' depositing a uniform coating of oil so thin that .10 gram of oil covers both sides of the sheets in a base box, or one pound of oil covers about 2,000,000 sq. ft. of sheet surface.

The upper value of uniform film thickness depends upon the time the oil vapor is in contact with the strip and the temperature of the strip. The time that the vapor is in contact with the strip of course is related to the speed of the strip and the length of the vapor chamber. In the process described, with the strip travelling at about 250 feet per minute through a vapor chamher about 5 feet long, we can obtain uniform oil thickness corresponding to about .40 gram of oil per base box or about 500,000 sq. ft. of surface per pound of oil. Tinplate coated by our process with oil films between the above-mentioned figures withstands the vicissitudes of storage and shipment with little damage, yet can be lacquered and retains the lacquer coating well.

- vaporing chamber, means for It will be understood also that the use of our apparatus is not confined'to t'inplate butmay be used to coat any thin, uniform film of oil.

The invention is not limited to the preferred embodiment which has been given merely for. purposes of illustration, but may 'be otherwise embodied or' practiced within following claims.

We claim:

1. Apparatus for applying a uniform film of oil to sheet metal, which comprises a vaporizing chamber, a cooling chamber connected to the passing the sheet metal continuously through the vaporizing chamber. and cooling chamber, means in the vaporizing chamber for atomizing oil with air to form a mist of oil particles suspended in the air, and

means in the vaporizing chamber ior heating the mist to a temperature sumcient to vaporize the oil particles, the cooling chamber providing means for condensing the oil vapor on the sheet metal.

2. Apparatus for applying a uniform film of oil to sheet metal, which comprising a vaporizing chamber, a cooling chamber connected to the vaporizing chamber, means forpassing the sheet metal continuously through the vaporizing chamber and cooling chamber, means in the vaporizing chamber for atomizing oil with air to form a mist of oil particles suspended in air, at least one baffle interposed between said atomizing means and the strip, and means for maintaining the baffle at a temperature suflicient to vaporize the oil particles, the baffle being arranged so that no oil particles can impinge on the sheet metal, the cooling chamber providing means for condensing the oil vapor on the sheet metal.

the scope of the= metal plate or strip with a ing means comprising-a particles can impinge,

3. Apparatus for applying a uniform film of oil to sheet metal, which comprises a vaporizing chamber, a cooling chamber connected to the vaporizing chamber, means for passing the sheet metal continuously through the vaporizing chamber and cooling chamber, means in the vaporizing chamber for atomizing oil with air to form a mist of oil particles suspended in air, the atomizplurality of nozzles each having an air passage and. a wheel associated with each air nozzle and adapted upon rotation to carry a film of oiLadjacent the outlet of the air passage and be atomized, at least one baffle interposed between said atomizing means and the strip, and means for maintaining the baiile at a temperature sufllcient to vaporize the oil particles, thebaflie being arranged so that no oil on the sheet metal, the cooling chamber providing means for condensing the oil vapor on the sheet metal.

' ROBERT A. WOOF'I'EB.

ROBERT H. SMITH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number 

